Swash plate compressors are generally known in the art. These compressors typically employ a cylinder block with a plurality of piston channels mounted on a drive shaft. A plurality of pistons are slidably disposed in the piston channels and are coupled to a swash plate that is also mounted on the drive shaft. In accordance with the rotation of the drive shaft, the swash plate pivots, causing reciprocal motion of the pistons within the piston channels, thereby alternately creating suction and compression strokes.
These compressors employ a variety of mechanisms that utilize the rotational force of the drive shaft to make the swash plate pivot, such as an actuating assembly with a slanted surface underneath the swash plate, as disclosed in U.S. Pat. No. 6,439,857 to Koelzer, which is assigned to the assignee of the present application, an assembly of rotating and non-rotating plates, as disclosed in U.S. Pat. No. 5,626,463 to Kimura, and a rotatable cylinder block, as disclosed in U.S. Pat. No. 5,394,698 to Takagi. As the swash plate pivots, the pistons reciprocate within the piston channels of the cylinder block, alternately drawing fluid to be compressed into the channels and subsequently compressing and discharging the fluid, all of which are hereby incorporated herein by reference.
In this way, the rotational force of the shaft is converted into axial motion of the pistons, enabling the pistons to alternately perform the functions of suction and compression, and thus, fluid is first drawn into a piston channel and is subsequently compressed and discharged from the piston channel.
In order to permit fluid to be drawn into, and subsequently discharged from, the piston channels, these compressors typically include a compressor head having inlet and outlet valves, or separate valve plates disposed between the compressor head and the cylinder block having such valves, which regulate the inflow and outflow of the fluid. These valves permit the piston channels to communicate with inlet and outlet channels, and ultimately, inlet and outlet ports, in the compressor head.
One disadvantage of these compressors, however, is that they must facilitate both the entry of uncompressed fluid from the compressor head in one direction and the discharge of compressed fluid to the compressor head in the opposite direction. Therefore, the compressor head must be designed with both inlet and outlet ports in the compressor head that each exclusively communicate with corresponding channels and valves, in order to permit the fluid to alternately flow in opposite directions and prevent the backfeeding of this fluid. Such assemblies tend to be difficult and costly to manufacture, and further, often entail multiple parts that are difficult to assemble.
Another disadvantage of these compressors is that the swash plate assemblies typically include at least one bearing facilitating the translation of the rotational motion of the drive shaft to the axial motion of the pistons within the piston channels. Such bearings may include, for example, a bearing coupling an inner part of the swash plate, which rotates with the drive shaft, and an outer part of the swash plate, which is coupled to the pistons, such as the assembly disclosed in U.S. Pat. No. 6,439,857 to Koelzer. Similarly, such bearings may include a bearing by which the pistons are coupled to the swash plate, or a bearing by which another device that facilitates the efficient operation of the swash plate is coupled thereto.
In order to overcome this disadvantage, it has been proposed to use a swash plate compressor having a cylinder block defining a swash plate chamber therein, the cylinder block having an inlet port that permits a fluid to flow into the swash plate chamber and cool the bearings therein, such as the compressor disclosed in U.S. Pat. No. 4,963,074 to Sanuki. Such compressors employing an inlet port in the cylinder block, however, suffer from several disadvantages. First, because the path of air flowing through the inlet port intersects with the piston channel, the port is often obstructed. Moreover, the fluid must pass over the inner walls of the cylinder block, which obviously have been heated due to the frictional force resulting from the pistons reciprocating in the piston channels, thereby increasing the temperature of the fluid and decreasing its ability to cool the bearings in the swash plate chamber.
What is desired, therefore, is a method and apparatus for compressing fluid that employs an arrangement for receiving and discharging fluid that is not complex. What is further desired is a method and apparatus that permits the fluid to be compressed to also be used to cool at least one of the bearings employed by the apparatus.